Welded casing joint



Fbv 18. 19 41. 5, DlESCHR- 2,232,593

wawsn Casme JOINT Filed Feb. 1, 1939 i INVENTOR. B M Y FM ATTORNEYS.

Patented Feb. 18, 1941 UNITED STATES PATENT- ormer,

waumn CASING JOINT Samuel E. Diescher, Pittsburgh, Pa., assignor to S. Diescher & Sons, Pittsburgh, Pa, a partnership consisting of Samuel August P. Diescher E. Diescher and Application February 1, 1939, Serial No. 254,028 1 Claim; (o1. 2s5-111)' This invention relates to welded joints for tubular members and more particularly is concerned with welded joints for oil well casing and.

the like.

.Heretofore,it has been the standard practice to line drilled well holes, and particularly deep holes as made in drilling for oil, with pipe or casing which has been connected end to end, usually by threaded joints. Sometimes the joints are made by threading each end of the casing with a male thread and then employing a female coupling sleeve. Again, the ends of the casing have been formed with complementary male and female joints. Threaded joints, regardless of the type, I

, various strings of casing'forming the complete casing program to be nested or'positioned one inside the other. The larger the starting hole size is, the greater is the cost of drilling the well with a particular finishing hole size, since a greater amount of earth has, to be removed and a greater tonnage of casing must be employed. Moreover, such threaded casing jointshave usually had a low efilciency (joint efliciency equals strength of joint divided by strength of the'casing proper) so that when subjected to high tensional stresses, as for example when the casing is being set into a very deep well or is being pulled out of a well,-the joints were'apt to fail. Further, whencasings'are subjected to high fluidpressure and heavy tension, as occurs in deep wells, threaded joints have beenfound to leak.

It has been proposed heretofore to reduce the cost of casing an oil well and to avoid leakage at the jointsby welding the lengths of casing together end to end and thereby eliminatethe threading operation. casing end to end which has been employed is to form one end 'of each casing length with a bell which isadapted to receive the plain spigot end on the other end of another length of casing. The end of the bell is then welded to the'side wall at the end ofthe spigot to provide what might be termed a fillet lap weld joint between the casing lengths. This procedure saves the cost of threading, but the'overall diameter of the joint is not materially reduced so that the advantage of having the smallest possible starting One manner of welding' hole size for a given finishing hole size is not obtained. Moreover, it has been proposed to butt weld casing lengths end to end, but so far as I am aware, this has not met with entire success due, among other causes, to the difficulty of making entirely good butt welds with the easing lengths end to end and in a vertical position.

Likewise, I have found that both the butt and bell and spigot types of welds are usually open to the objection that the joint efficiency is low,

and the internal bore of the-welded casing is either not continuous and smooth or, in the case of butt-welded casing, is actually clogged or interrupted with inwardly extending welding metal. Such welding metal or other change in diameter of the bore of the casing in the region of the joint prevents the use of swabs, packings or the like in casing or materially reduces the life and effectiveness thereof, it they are employed. Further, I have found that the ordinary skilled welder finds great difficulty in satisfactorily welding oil well casingtogether end to end by known methods and using known types of joints.

It is the'general object of my invention to avoid and overcome the foregoing and other difli- I culties of and objections to known joints for oil well'casing in particular, and tubular members in general, by the provision of an improved welded joint which can be rapidly and inexpensively made by the ordinary welder. with his usual equipment to provide a joint having high efliciency, a smooth internal bore and a minimum outside diameter.

Another object of my invention is to provide a welded joint for oil well casing or the like and wherein the joint is adapted to resist, without failure, tensional and collapsing stresses of an amount which cause failure of the casing bodyproper.

Another, and more specific, object of my invention is the provision of a welded joint for oil well casing or the like in which the aligning andspacing of the joint parts is facilitated by means of a taperedwedge ring which serves also to prevent any introduction of welding metal into the continuous bore of the joint.

Another object of my invention is toprovide I a welded joint for oil well casing or the like in which the cross sectional area of the weld is substantially greater than the cross sectional area of the casing body proper whereby the joint efliciency is at least approximately per cent or more'while maintaining the external diameter of the joint at a minimum.

The foregoing and other objects of my invenavoid stress concentrations.

tion are achieved by the provision of awelded joint including a pair of tubular members having upset ends of like internal diameters, and an aligning ring having a bore of the same internal diameter as the diameter of the tubular members. The aligning ring is received in counterbores in the ends of the tubular members and interlocking means on the ring and the counterbores hold the ends of the ring against movement inwardly of the bore. Completing the combination are means welding the ends of the tubular members together and to the aligning ring. Usually the aligning ring is formed of a double wedge shape and the counterbores are tapered to a contour complementary to the aligning ring. The aligning ring also preferably includes a circumferential rib which extends between the ends of the tubular members and which melts during the welding operation, after aiding in centralizing the welding arc, to reduce the flow of heat to the radially inner surface of the aligning ring. The adjacent ends of the tubular members to be welded are each formed with acomplementary bevel which together define a welding groove and usually the bevel on the end of the lower tubular member is sufficiently close to radial that it supports the fluid weld metal within the angle of repose when the tubular members are welded in a vertical position. Preferably the ends of the tubular members are upset externally prior to machining and assembling the ends for welding so as to provide a welding area approximately 25 per cent greater than the cross sectional area of the casing proper.

For a better understandingof my invention reference should be held to the accompanying drawing which illustrates one embodiment thereof and wherein Fig. 1 is a side elevation of a welded joint embodying the principles of my invention with portions thereof being broken away to illustrate the joint in cross section; and Fig. 2 is an enlarged vertical cross sectional view of a portion of the welded joint shown in Fig. 1.

While my improved welded joint may be used in conjunction with tubular members of various kinds and employed for many purposes, nevertheless my invention is particularly concerned with the provision of an improved welded joint for oil well casing and the like and accordingly has been position. Preferably, the ends of the casing lengths Ill and 12 are externally upset over a short distance, 'as for example approximately 5 inches in a casing having approximately a 6-inch internal diameter. The upset portions of the casing lengths are merged gradually into the portions of the casing which are not upset so as to the ends of the casing lengths is done to increase the radial thickness of the casing endsso that the cross sectional area of the weld is substantially greater than the cross sectional area of the casing body proper, all as hereinafter more fully discussed.

Each end of the casing lengths l and I2 is formed with inwardly tapered counterbores l4 and I6 which receive an aligning and spacing ring, indicated as a whole by the numeral l6 and formed with an internal diameter or bore of The upsetting of length without failure.

the same dimension as the internal diameter or bore of the casing upsets. Thus, the internal diameter of the casing lengths and the joint is constant and provides a smooth uninterrupted surface which permits the free use of swab packings and the like in the inside of the casing which is qute advantageous. The outer surface of the aligning and spacing ring I8 is formed as a double frustum of a cone so that it engages in complementary relation with the tapered surfaces of the counterbores l4 and I6, and thus acts to align the casing ends with each other and hold them in accurately positioned and spaced relationshipwhich is highly advantageous when the casing is of the seamless tube type possessing wall eccentricity. I preferably machine the counterbores l4 and I6 while holding each casing centeredon its bore rather than centered on. its outside surface.

An important feature of my invention is the provision of interlocking means between the aligning ring I8 and the counterbores I4 and I6, which means prevent the radially inward movement of the ends of the aligning ring 18 during the welding of the joint orat any time thereafter. These means may obviously take a plurality of forms but conveniently comprise overhanging shoulders 20 and 22' at the ends of the counterbores I 4 and I6 which engage in locking relation with chamfers or beveled surfaces 24 and 26 on the ends of the aligning ring l8. The interlocking action provided between the chamfered ends of the aligning ring l8 and the over hanging shoulders at the inner ends of the counterbores l4 and I6 serve to perform the desired function when the two casing lengths are forced onto the aligning ring merely by the weight of the upper lengths of casing to be joined.

I preferably form the aligning ring l8 with a circumferentially continuous, outwardly extend:- ing rib 30 which extends into the space between the ends of the casing lengths. I have found that the size and position of the rib 30 should be substantially that clearly illustrated in Fig. 2.

in order to provide the best type of welding action. During the welding of the joint the rib 3U attracts the welding arc in the course of applying the first bead and thus not only centralzes the initial deposit of welding material as the rib melts down, but also insures the positive welding of the ring ill to the welding metal and the ends of the casing lengths. Further, the melting down of the rib reduces the temperature of the aligning ring and particularly the radially inner surfacethereof so that undesirable oxidation of the ring -is eliminated. The radial thickness of the ring,

approximately twenty-five per cent of that of the upset portion of the casings, keeps the temperature at the radially inner surface thereof at a point sufficiently low that undesirable oxidation of the ring surface is avoided. I have found that when the ring is proportioned to perform in the manner just stated it has ample size and area to take the stabbing pressure of the upper casing The extreme ends of each of the casing lengths I0 and I! are formed with a bevel or chamfer as at 34 and 36 which are complementary to each other and together define the welding groove.

It will be noted that the bevel or chamfer 36 on the-lower casing end is relatively flat in that it is substantially radial. Usually this bevel is approximately from the radial so that fluid weld metal positioned thereon is carried within the angle of repose and will not roll or slide off the 7 outlining the method of making my improved bevel. This is advantageous for the reason that the ordinary welder can perform a satisfactory job-without the constant annoyance of working so that the weld metal will not flow out of the welding groove. The beveled surface 34 forms an angle of approximately 35 with the radial,

on the aligning ring it. Thus, when welding metal is placed in the welding groove the welding metal flows down and around the circumferential rib 30 until the rib material has become molten.

It is believed that the construction of my improved joint for tubular members, and particularly oil well casing, will be understood from the foregoing detailed description. However, briefly joint, the lower casing length 12, positioned in the drilled hole orin a special hole in the derrick floor and upset and machined to the contour shown, first receives the aligning ring ll which is merely fitted down into the tapered counterbore It in the end of the casing. Thereafter,

the casing length In is raised by the draw works and elevator or by other suitable means and the lower end thereof is moved down to bring the counterbore l4 over the end of the aligning ring l8 after whichthe elevator or other lifting means is paid off to cause the full weight of the casing length to forcethe two lengths of easing locking the ends of the aligning ring I! in the removed, a second, and usually a third, bead of counterbores l4 and It so that any tendency .for the aligning ring l8 to distort under the welding heat is not translated into radially inward movement of the ends of the aligning ring. Once the tack welds are made a first bead of welding material is laid completely around the bottom of the welding groove. After the first bead ofwelding material has its slag coating welding material is laid around the welding groove and the welded joint is finished.

From the foregoing it will be recognized that the objects of my invention have been achieved by the provision of an improved welded jointpartlcularly adapted i'or'use in conjunction with oil .well casing and the like. By making the ends of the casing upset externally I am able f to increase the cross sectional area of the welded portion of the joint by an amount approximately twenty-five per cent greater than theeross lectional area of the casing body proper and thus make certain that the joint emciency is at least one hundred per cent. This increase in the cross sectional area of the welded portion of the joint takes care of any inclusions or blow holes in the weld which often occur, and, moreover, al- 6 lows for the unequal cooling stresses normally present in, the weld. These stresses, which are known to be present in the weld, tend to reduce the joint efficiency but I have compensated for them by increasingthe cross sectional area of thejoint, as already explained.

My im-pro'ved welded'joint has a smooth internal bore of the same diameter as the bore of the casing body proper, and therefore the joint is particularly adapted to permit eflective use of swab packings and the like in thebore of the casing, which is highly advantageous.

'Casings that are inherently smooth inside and regular in bore will have with this joint no interior irregularities destructive of swab packings and may even make possible the pumping of wells with swab-like equipment adapted to that purpose.

JI'he outside diameter of the joint has been kept at the minimum required to provide the desired joint einciency and therefore casing costs are likewise kept at the smallest possible figure. Furthermore, the characteristics ohny improved joint permit the ordinary welder to rapidly, and eiiiciently provide the desired joint with a mini- 30 mum of equipment andtime and without any possibility that the welding metal will 'in any way interrupt or extend into the bore of the joint. The upset ends of the casing in the region of the joint increase the resistance to collapse of the joint to such an extent that the body of bersin other than a vertical position. Therefore, while I havein accordancewith the patent statutes particularly illustrated and described one embodiment of my invention, it will be un-- 50 derstood that I am not to be limited thereto or thereby but that my invention is defined in'the appended claim.

Iclaim: A welded'joint comprising a pair of tubular members of a like internal diameter, andam aligning ring having a bore of the-same internal diameter as the diameter of the tubular members, said aligning ring being'received in counterbores in the ends of the tubular members and being provided with beveled ends interlockingly engaging overhangig shoulders at the inner ends of the counterbo es for holding the ends of the ring against movement inwardly of the bore under welding heat, the ends of the tubular 66 members being adapted to be welded together and to the aligning ring.

SAMUEL E. DIESCHER. 

